Spring Refactor MimeType BitSet initialization for improved readability and maintainability

Refactored BitSet initialization to remove repetitive set calls by introducing a char array (SEPARATORS).

• Enhanced readability: Separator characters are now defined in one place, making the code easier to understand.
• Improved maintainability: Adding or modifying separator characters is now simpler, requiring updates only to the SEPARATORS array.

Comment From: bclozel

Thanks for the proposal but I don't think this improves readability nor maintenance.